1. Field of the Invention
The present invention relates generally to a recording medium handling mechanism in a library apparatus, and more particularly to a mechanical hand of an accessor for automatically exchanging a recording medium cartridge between a cell unit for accommodating the cartridge and a recording medium drive unit for performing read/write of data from/to the cartridge.
2. Description of the Related Art
A magnetic tape unit is known as an example of an external storage for a computer. An open-reel type magnetic tape unit using a 0.5-inch-wide tape is used in the art, but the operation is troublesome. So, there use is spreading of an automatic threading unit capable of automatically threading a tape by setting a reel on a support plate. Further, a magnetic tape cartridge has recently been used widely for the purpose of reducing a burden of an operator. In the magnetic tape cartridge, a tape of the same width as that of the open-reel type magnetic tape unit is used, and the tape is automatically drawn and threaded from a reel accommodated in a case.
A required number of such magnetic tape cartridges are entered in a magnetic tape library apparatus, and are selectively loaded to perform read/write of data. The magnetic tape library apparatus includes a cell unit having a plurality of cells for accommodating the magnetic tape cartridges, a magnetic tape drive unit for performing read/write of data from/to the selected magnetic tape cartridge, and an accessor for automatically exchanging the magnetic tape cartridge between the cell unit and the magnetic tape drive unit.
The magnetic tape library apparatus further includes a cartridge entry unit for entering the magnetic tape cartridges into the library apparatus and an automatic cartridge exit unit for automatically ejecting the magnetic tape cartridges from the library apparatus. Such a magnetic tape library apparatus has recently been used as a mass external storage for a computer, and it is required to reliably operate even when unmanned.
The accessor is provided with a hand mechanism for gripping the magnetic tape cartridge. The accessor serves to deliver the magnetic tape cartridge gripped by the mechanical hand among the cell unit, the magnetic tape drive unit, the cartridge entry unit and the automatic cartridge exit unit. The mechanical hand in the prior art includes a grip hand constructed of an upper finger and a lower finger. The lower finger is mounted pivotably about a horizontal axis. That is, the lower finger is adapted to be vertically opened and closed to grip and release the cartridge.
In such a conventional mechanical hand, the lower finger is opened in the cell accommodating the magnetic tape cartridge, so that it is necessary to define a space for permitting movement of the lower finger in the cell. Accordingly, a height of the cell must be made large. Further, as a cartridge insert opening of the magnetic tape drive unit is smaller in size than that of the cell, it is necessary to provide an automatic loading unit before the cartridge insert opening of the magnetic tape drive unit, so as to surely insert the cartridge. Accordingly, the magnetic tape library apparatus becomes large in size, and a cost increase is caused.